Officials at Nasa have been given an unexpected gift by American spy chiefs: a pair of space telescopes, each as large as the Hubble observatory.

The huge instruments were designed by the National Reconnaissance Office (NRO), a secretive intelligence agency, to peer down on sites in the Middle East and former Soviet Union. However, the project was cancelled and now Nasa has been presented with the leftover instruments. One group of astronomers has already begun work on plans to use a telescope to help in the hunt for life on other worlds.

“This is a gift that we have to take advantage of,” said Dr Matt Mountain, director of the Space Telescope Science Institute in Baltimore, Maryland. “These are very large telescopes, and from their design specifications they appear ideal for carrying out large surveys of the heavens, including searches for Earth-like worlds orbiting stars near our solar system.”

The two telescopes donated by the NRO have mirrors 2.4 metres in diameter – the same as the Hubble observatory’s – and from space they could spot “a dime sitting on top of the Washington Monument”, according to a Nasa official.